Method for punching slug from workpiece

ABSTRACT

A punched slug removal system for punching a slug from a workpiece and removing the punched slug. The system includes a punch having a reciprocating travel path with a transition point where the punch changes direction. A die plate has an aperture into which a die bushing may be disposed. The die bushing provides support for the workpiece and has an opening through which the punch and a slug pass. A manifold supports the die plate and (if present) the die bushing and has a distribution channel and an orifice which direct a gas flow onto a slug attached to the punch in a direction perpendicular to the reciprocating travel path of the punch to remove the slug from the punch. The distribution channel is tapered to increase the velocity of the gas flow. The orifice is positioned at the top of the manifold adjacent the transition point of the reciprocating travel path of the punch. The manifold extends into the aperture of the die plate, reducing the cross sectional area of the aperture, and has a step formed under the punch. The system also includes a vacuum, offset relative to the punch and applied to the side of the punch opposite the orifice, to enhance removal of slugs from the punch.

This application is a divisional of U.S. patent application Ser. No.08/904,339, filed on Jul. 31, 1997, now U.S. Pat. No. 6,003,418.

TECHNICAL FIELD

The present invention relates generally to a punch which forms holes inthin sheet material and, more particularly, to an improved punch with apositive slug removal feature to facilitate punching in materials suchas green ceramic sheets.

BACKGROUND OF THE INVENTION

A plurality of unfired (green) ceramic sheets or tapes are used in themanufacture of multilayer ceramic substrates for integrated circuitsemiconductor package structures. Via holes are punched in the ceramicgreen sheets to form the paths for electrical interconnections throughthe sheets. The step of punching the via holes in ceramic green sheetspresents formidable engineering problems in view of the small size anddensity of the holes and of the complex hole patterns needed. The sheetsthemselves are typically thin: only about 0.2 mm (8 mils) thick.

It is convenient to punch via holes with a tool of the type disclosed inU.S. Pat. No. 4,425,829 issued to Kranik et al. In this type of tool, aplurality of punch elements are arranged in a grid on a punch head andare indexed over the green sheet which is covered by an interposer mask.The interposer mask contains openings where holes will be punched. Whenthe punch elements contact the interposer mask, as the punch head ismoved downwardly, a hole will be punched where the openings occurbecause the punch element will pass through the openings in theinterposer mask and then through the ceramic green sheet. In other areascovered by the interposer mask (i.e., where holes are not desired), theinterposer mask will cause the punch element to be retracted into thehead. The green sheet is sequentially indexed through a predeterminednumber of positions to complete the punching of a sheet.

It is essential that the punching operation produce products free fromdefects. A single defect can potentially render a green sheet unsuitablefor further processing. It is also essential that the punching operationbe rapidly and accurately performed. Each green sheet can contain over100,000 punched holes. Of particular concern is the adherence to the tipof the punch of a slug punched from the sheet. The inherent adhesioncharacteristics of the unfired green sheet are amplified by the largepunching force applied over the small area of the punch tip. Thediameter of the punch tip can be as small as 0.13 to 0.15 mm (5 to 6mils) in current application and is expected to be 0.10 mm (4 mils) orless for advanced substrates, resulting in a pressure at the punch tipon the order of 2,700 kg/cm². If the punch slug adheres to the punch,the slug may be drawn back into the punched hole, causing a substratedefect. To eliminate the likelihood of such defects, it has beenstandard practice to use two punch strokes for each hole. This practicegreatly increases green sheet processing time.

The problem of slug adhesion to the punch is not limited to the punchingof ceramic green sheets; rather, the problem has been discussed in otherpunching application references. One method adopted in punchingapparatus for the removal of punch slugs is the use of eitherpressurized air or a vacuum to force the slug from the punch. Certainreferences disclose apparatus in which air is channeled through thepunch to remove the slug from the tip of the punch. An example of such areference is U.S. Pat. No. 4,628,780 issued to Hicks. This method is notpractical, however, for punching extremely small diameter holes. Otherapplications either direct air into or apply a vacuum to a chamber belowthe punch to clear the slugs and do not directly address the problem ofslug adherence.

The use of air flow slug removal methods in ceramic green sheet punchingto achieve single stroke punching is disclosed in U.S. Pat. No.5,111,723 issued to Andrusch et al. and U.S. Pat. No. 4,425,829 issuedto Kranik et al. Kranik et al. teach a tube protruding into the diebushing which upwardly injects air into the die cavity below thepunching area. This air flow induces circulation in the die bushingcavity which assists in forcibly removing slugs from the punch. Thearrangement does not provide the repeatability necessary to achievesingle stroke punching.

Andrusch et al. teach a single stroke punch apparatus which includes apunch and a bushing retention die plate. A support bushing is mounted inthe die plate and provides support for the workpiece. The supportbushing has a clearance for a punch. The apparatus also has a nozzle (or“slug removal bushing”) mounted in the die plate which provides aninternal passage for the removal of punch slugs from the apparatus. Aslug is punched from the workpiece through an opening in an end wall ofthe support bushing disposed in an aperture of the die plate. Thenozzle, the support bushing, and the bushing retention die plate definea flow passage allowing gas to flow in the die plate to the opening inthe support bushing. The flow passage includes a slot clearance betweenthe end wall at the top of the nozzle and the support bushing. The gasflow impinges on the slug attached to the punch tip proximate to the endwall of the support bushing and at the top of the nozzle to remove theslug from the punch through a slug removal passage in the nozzle.

The shape of the slot clearance helps to direct the gas flow downwardand away from the punch and the green sheet. U.S. Pat. No. 5,111,723 atcolumn 5, lines 36-37. Therefore, the gas flow is parallel to thedirection of travel of the punch and slug when the gas flow impinges onthe slug attached to the punch tip. The tangential force of the gas flowon the slug is sometimes insufficient to blow the slug from the punchtip. In addition, the slot clearance prevents a sealed surface betweenthe support bushing and the nozzle, thus allowing the rapid expansion ofgas (air) as it enters the region immediately below this interface.Without a sealed interface, the gas tends to expand too quickly into thevolume surrounding the punch tip and slug and is sometimes ineffectivefor blowing the slug from the punch tip.

These same problems arise for the punching tool disclosed in JapanPatent No. 5-057687 issued to Takumi et al. The die bushing of thepunching tool has an air lead groove and an air passage port formed inits periphery. The die bushing also has a central hole into which thepunch and slug pass. Air flows inward from the periphery of the diebushing and toward the punch through the air passage port. The airpassage port is formed obliquely so that it directs the air flowdownward and at a tangential angle into the central hole of the diebushing and onto the punch. In addition, the air rapidly expands in thecentral hole of the die bushing once it leaves the air passage port.

The punching tool disclosed in Japan Patent No. 5-261454 issued toTomohiro similarly incorporates a slanted bore in the periphery of thedie bushing. The angle of the bore is specifically set at about 10-80degrees to assure that the air flow is directed downward toward thepunch. The diameter of the bore is 1 mm or less and the force of the airflow is apparently 0.5 to 5 kg.

U.S. Pat. No. 5,214,991 issued to Shimizu et al. discloses a punchingapparatus in which compressed air is made to flow at high speed parallelto the direction of travel of the punch and through the hole just formedby the punch in the green sheet. A gap is formed between the punch pinand the peripheral wall of the opening (through which the punch passes)in the stripper member disposed above the green sheet. The air flowsdownward through that gap where it is then sucked toward the base of thedie by a suction mechanism. The downward air flow can blow a slug offthe punch tip and carry the slug toward the suction mechanism.

Although the configurations discussed above have been useful in removingslugs from the punch tip, none of the configurations provide the 100%slug removal which is required for single stroke punching. A 99.9% slugremoval rate on a green sheet containing 100,000 holes results in 100defects per sheet, any one of which renders the sheet unacceptable forfurther processing. The problem can be further appreciated byconsidering that a defect may not be detected until the green sheet islaminated into a substrate containing 60 or more layers. Thus, theconventional tools used to remove a punch slug are not effective to thedegree needed when punching 0.2 mm (8 mils) thick green sheets in highvolume manufacturing. The slug that is punched out is not alwaysremoved, resulting in via blockage.

The deficiencies of the conventional punch configurations show that aneed still exists for a system which will precisely direct an air flowat a punch tip to remove the punch slug and thus allow single strokepunching. To overcome the shortcomings of the conventional punchconfigurations, a new punched slug removal system is provided. An objectof the present invention is to provide a single stroke punch systemwhich offers improved punch slug removal.

Another object is to avoid a design in which a separateconverging-diverging nozzle fits within the die bushing of the punchtool to achieve air flow velocities sufficient to remove the slug fromthe punch tip. Yet another object is to avoid a design in which air flowpassages are formed through the punch, the punch bushing, the diebushing, or the die plate. A related object is to reduce the costrequired to build and maintain a punched slug removal system.

It is a further object of the present invention to provide a punchedslug removal system which precisely directs an air flow at the slugadhered to a punch tip. Another object is to assure that the maximumforce of the air flow is applied to the adhered slug for the maximumlength of time, thus making the air flow more effective. It is stillanother object of the present invention to prevent the rapid expansionof the gas which reduces the effectiveness of the gas for blowing offthe slug.

SUMMARY OF THE INVENTION

To achieve these and other objects, and in view of its purposes, thepresent invention provides a punched slug removal system for punching aslug from a workpiece and removing the punched slug. The system includesa punch having a linear reciprocating travel path with a transitionpoint where the punch changes direction (i.e., the transition point isdefined as the point in the reciprocating travel path where the punchchanges direction at the end of its downward travel and before it beginsits upward travel, the precise point of reciprocation). A die plate hasan aperture into which a die bushing may be disposed. The die bushingprovides support for the workpiece and has an opening through which thepunch and a slug pass. A manifold supports the die plate and (ifpresent) the die bushing and has a distribution channel and an orificewhich direct a gas flow onto a slug attached to the punch in a directionperpendicular to the reciprocating travel path of the punch to removethe slug from the punch. The distribution channel is tapered to increasethe velocity of the gas flow. The orifice is positioned at the top ofthe manifold adjacent the transition point of the reciprocating travelpath of the punch. The manifold extends into the aperture of the dieplate, reducing the cross sectional area of the aperture, and has a stepformed under the punch. The system also includes a vacuum, applied tothe side of the punch opposite the orifice and offset relative to thepunch, to enhance removal of slugs from the punch.

The invention also encompasses a method for punching which includesproviding a workpiece proximate a surface of a die plate defining anaperture. The method further includes punching a slug from the workpiecethrough the aperture. A gas flow is directed through a distributionchannel defined in a manifold supporting the die plate. The gas flowimpinges on the slug attached to the punch in a direction perpendicularto the reciprocating travel path of the punch to remove the slug fromthe punch.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the invention.

BRIEF DESCRIPTION OF THE DRAWING

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasizedthat, according to common practice, the various features of the drawingare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawing are the following figures:

FIG. 1 is a cross-section of the slug removal elements and punch tool ofthe present invention;

FIG. 2 is a perspective view of the die bushing, die plate, and manifoldforming the die assembly according to the present invention, with thecomponents separated for clarity;

FIG. 3 is a top view of the region extending from the orifice of thedistribution channel to the side wall of the vacuum channel of the dieassembly illustrated in FIG. 2;

FIG. 4 is a perspective view of the die plate and manifold forming thedie assembly without a die bushing according to an alternativeembodiment of the present invention; and

FIG. 5 is a cross-section of a conventional slug removal and punchapparatus.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawing, wherein like reference numerals refer tolike elements throughout, FIG. 5 shows a cross-section of a conventionalslug removal and punch apparatus. As illustrated, apparatus 1 of FIG. 5includes a punch 10. Although punch 10 may be an individual punch, it ispreferably one of multiple punches in a punch head as shown in U.S. Pat.No. 4,425,829 issued to Kranik et al. Punch 10 is located in punchhousing 8 by punch bushing 11. Punch 10 punches a workpiece 12, which ina preferred embodiment is a ceramic green sheet, removing punch slug 50.(The present invention works with workpiece materials other than greensheets.) Slug 50 often adheres to the end or tip of punch 10. Aninterposer 18 defining a punch pattern may be placed between punchhousing 8 and workpiece 12 if spacing allows.

A die plate (or die shim) 14 defines an aperture (or bushing receivingfeature) 6. In the preferred multiple punch embodiment, die plate 14forms a series of apertures 6 which open on the surface 4 of die plate14 which faces workpiece 12. Die plate 14 also includes a port 16 forintroducing gas flow into aperture 6. The gas may be any type of gassuitable for removing punch slug 50 from punch 10. Although compressedair is preferably used for slug removal, compressed nitrogen is alsosuitable.

Apparatus 1 of FIG. 5 has a die bushing 13 which supports workpiece 12.Die bushing 13 is pressed into die plate 14 and, specifically, ismounted in aperture 6. The top 15 of die bushing 13 has a workpiecesupporting surface 2 which includes an opening 3 providing clearance forpunch 10 and attached slug 50. Workpiece 12 rests on die bushing 13rather than on die plate 14, which prevents marring damage to workpiece12. In the multiple punch configuration, of course, a whole series ofdie bushings 13 define the support surface 2 on which workpiece 12rests.

Port 16 in die plate 14 meets passage 17 in die bushing 13 to form aflow path for the gas flow. A manifold 20 may be provided under dieplate 14. A vacuum 30 may be provided both to direct the gas flow and tofacilitate removal of slug 50 from apparatus 1.

The conventional slug removal and punch apparatus illustrated in FIG. 5discloses injecting air from passage 17 in die bushing 13 to remove slug50 from punch 10. This arrangement has not provided the repeatabilitynecessary to achieve single stroke punching. The usable length “at” ofpunch 10 is limited by the difficulty of fabricating an accurate, smalldiameter punch 10 suitable for the rigors of production punching and bythe requirement of machining radius “b.” This usable length must extendthrough wall thickness “c” of punch bushing 11, workpiece 12 thickness“d,” and the wall thickness “e” of die bushing 13. The accumulation ofthese dimensions and accompanying tolerances results in a minimalprotrusion of the punch beyond top 15 of die bushing 13. It is verydifficult to cause passage 17 to direct air precisely at top 15 becauseof the required wall thicknesses and tolerances involved. In particular,the necessary alignment of passage 17 in die bushing 13 with port 16 indie plate 14 creates tolerance problems and renders alignment andassembly more difficult. These problems are aggravated in anon-programmable multiple punch which, in addition to the componentsalready discussed, requires interposer 18 having a thickness “f.”

Turning to FIG. 1, a cross-section of the slug removal elements andpunch tool of the punched slug removal system 60 of the presentinvention is shown. System 60 for accomplishing the slug removaloperation includes a plurality of punches 10, a corresponding pluralityof die bushings 13, a die plate 14, and a manifold 20. Die bushings 13are preferably tungsten carbide and have a thickness of about 0.8 mm (32mils). Die plate 14 is typically 0.5 mm (20 mils) thick molybdenum orstainless steel. Punch 10 forces the ceramic material or workpiece 12(not shown) into opening 3 of die bushing 13, causing the ceramic tofracture and dislodge at the interface between punch 10 and die bushing13. Die plate 14 serves two purposes: it retains die bushing 13 at afixed position relative to punch 10 and covers the distribution channels80 in manifold 20 when die plate 14 and manifold 20 are assembledtogether. Manifold 20 supports die plate 14 and die bushings 13 andallows the distribution of high pressure fluid (gas) and vacuum for slugremoval. An adhesive 90 having a maximum thickness of about 0.025 mm (1mil) may be disposed between manifold 20 and die plate 14 and each ofdie bushings 13. Die bushings 13 are retained in die plate 14 both by apress fit and by adhesive 92.

FIG. 2 is a perspective view of die bushings 13, die plate 14, andmanifold 20 forming the die portion of system 60 according to thepresent invention. The components have been separated in FIG. 2 forclarity. Sleeves 22 are provided to facilitate alignment and joining ofthe components. For the embodiment illustrated, and for purposes ofexample only, there are 144 die bushings 13. A plurality of distributionchannels 80 are provided in manifold 20. Fluid flow through eachdistribution channel 80 and the force induced by the fluid flow removesslug 50 from the tip of punch 10 as described more fully below.

A comparison of FIGS. 1 and 5 illustrates the improvements achieved bythe present invention. Specifically, port 16 in die plate 14 and passage17 in die bushing 13 have been replaced by distribution channel 80ending in an orifice 82 in manifold 20. Orifice 82 is precisely locatedat or near the top of manifold 20 as illustrated in FIG. 1. The locationof orifice 82 in manifold 20, and not in another component such as thedie plate, the die bushing, the punch, or the punch bushing has severaladvantages.

The improved placement of orifice 82 in manifold 20 allows a jet offluid to impinge upon slug 50 that is attached to the tip of punch 10while punch 10 is in the transition point of its reciprocating travel.Fluid flow hits the tip of punch 10 at the very bottom of its stroke(bottom dead center)—at precisely the best point in the travel of punch10—assuring that fluid impinges on the tip of punch 10 and slug 50, ifslug 50 has adhered to the tip, for the maximum time. Thus, fluid isintroduced through orifice 82 at the top of manifold 20 and not throughanother component or another location. Orifice 82 is provided at a mostefficient location where the fluid blast impinges directly on slug 50 atthe point of maximum stroke of punch 10.

Distribution channel 80 has a “T”-shape and is provided with a taper 84so that the minimum cross section of distribution channel 80 exists atorifice 82. The cross section of orifice 82 is about 0.20 to 0.38 mm (8to 15 mils) square. Orifice 82 is positioned at the end of the “head” ofthe T-shaped distribution channel 80. The cross section near themidpoint of each leg of the head is about 0.75 mm (30 mils) square. Themaximum size of distribution channel 80, exhibited by the “tail” of theT-shaped distribution channel 80, is about 3.175 mm (125 mils). Thetapered configuration increases the velocity of the fluid exitingorifice 82 and avoids the need for a separate nozzle component. Thespecific configuration of distribution channel 80 shown in FIG. 1 ispreferred.

Orifice 82 is positioned close to the vertical travel path of punch 10.Preferably, orifice 82 is about 0.125 mm (5 mils) from the verticaltravel path of punch 10. Such proximity helps to assure theperpendicular direction of the fluid flow upon impact with punch 10 andslug 50 and, therefore, increases the force of the fluid flow on thoseelements.

The improved design of manifold 20 according to the present inventionincreases the maximum force on the tip of punch 10 and slug 50 overconventional designs. For the same pressure drop of 80 psi, the designof the present invention induces a force more than 30% greater than theforce induced by conventional designs. Therefore, the design of thepresent invention is more effective in removing slug 50 from punch 10.In addition, the design of the present invention applies the maximumforce for a longer time, also making it more effective.

When punch 10 passes through workpiece 12 (not shown), slug 50 entersthe fluid flow just below the top 15 of die plate 14 and is removed bythe fluid traveling perpendicular (ninety degrees) to the direction oftravel of punch 10 and slug 50. The perpendicular impact of the fluid onslug 50 is important; such impact maximizes the force component of thefluid on slug 50.

The fluid is preferably a gas. The gas may be compressed air, nitrogen,or other suitable gas provided by a compressed gas source 40. The gasleaves source 40 and enters distribution channel 80 in the tail ofT-shaped distribution channel 80. At the junction between the tail andhead of T-shaped distribution channel 80, the gas divides to form a gasflow A directed toward separate punches 10 through manifold 20. Gas flowA exits distribution channel 80 and manifold 20 at orifice 82, impingingon punch 10 and slug 50. The gas flow is then pulled perpendicularlyacross punch 10 and slug 50 in aperture 6 by a vacuum 30 forming gasflow B in a vacuum channel 32 having a side wall 34. Vacuum 30 ispositioned on the side of punch 10 opposite both orifice 82 and theimpinging gas flow A. Subsequently, slug 50 is pulled via gas flow Binto a debris collector (not shown).

The diameter of vacuum channel 32 is about 3.175 mm (125 mils). Gassource 40, distribution channels 80, apertures 6, vacuum channels 32,and vacuum 30 form a closed, sealed subsystem for the gas used inpunched slug removal system 60. The sealed subsystem provides a constantflow of gas for removal of slugs 50. Moreover, the flow is preciselydirected and does not simply fill the volume of aperture 6.

The center of vacuum channel 32 is specifically located off-centerrelative to punch 10. In other words, vacuum channel 32 is notpositioned directly under and concentric with punch 10. Rather, vacuumchannel 32 is offset relative to punch 10. This configuration assuresthat the gas flow will be pulled perpendicularly across punch 10 andslug 50 and will not change direction until the gas flow has gone beyondpunch 10 and slug 50.

Manifold 20 of the present invention extends part-way under die bushing13, filling some of the area under die bushing 13 and reducing thevolume of the region extending under die bushing 13. This reduced volumeallows for higher fluid force near the tip of punch 10 while keeping thetotal pressure drop across this region at acceptable levels. The rapidexpansion of gas (air) as the gas enters this region is reduced relativeto conventional designs. For the larger volume under die bushing 13shown in FIG. 5, for example, the gas may expand too quickly and may beineffective for blowing slug 50 off the tip of punch 10.

The extension of manifold 20 under die bushing 13 requires that a step70 be formed in manifold 20 to provide clearance for punch 10 and slug50. Step 70 also allows an accidentally broken punch to fall and beswept away by gas flow B (along with slug 50) to the debris collector,allowing easy maintenance. Step 70 has a height 72 of about 0.75 mm (30mils) and a width 74 of about 1.7 mm (68 mils) The interconnectionbetween distribution channel 80, step 70, and vacuum channel 32 isfurther illustrated in FIG. 3. Specifically, FIG. 3 is a top view of theregion extending from orifice 82 of distribution channel 80 to side wall34 of vacuum channel 32 of the die assembly illustrated in FIG. 2.

FIG. 4 is a perspective view of die plate 14 and manifold 20 forming thedie assembly without die bushing 13 according to an alternativeembodiment of the present invention. In this embodiment, aperture 6 ofdie plate 14 may be made smaller than aperture 6 of the embodiment shownin FIG. 1. Die plate 14 rather than die bushing 13 provides support forthe workpiece. Punch 10 and slug 50 pass through aperture 6 only ratherthan through both aperture 6 of die plate 14 and opening 3 of(non-existent) die bushing 13. Otherwise, the relationship between thecomponents of FIG. 4 corresponds to the relationship between the samecomponents of FIG. 1.

Implementation of the present invention allows single stroke punching.The invention essentially provides positive 100% punch slug removal,with minimal defective sheets, when used for punching ceramic greensheets and provides significant process time improvement over thepreviously practiced punching methods. The present invention avoids aseparate converging-diverging nozzle, often placed within the diebushing of conventional punch tools to achieve air flow velocitiessufficient to remove the slug from the punch tip. The present inventionalso avoids air flow passages in components such as the punch, the punchbushing, the die bushing, and the die plate. Consequently, the design ofthe present invention reduces the cost required to build and maintainpunched slug removal system 60.

The method for removing workpiece slugs 50 from a punch 10 allowed bythe punched slug removal system 60 of the present invention includes thesteps of providing a workpiece 12 proximate a surface 4 of a die plate14 defining an aperture 6; punching a slug from the workpiece through anopening 3 in a die bushing 13 disposed in the aperture 6; directing agas flow “A” through a distribution channel 80 defined in a manifold 20supporting the die plate and the die bushing; and impinging the gas flowon the slug attached to the punch in a direction perpendicular to thereciprocating travel path of the punch to remove the slug from thepunch. The method may also include inserting an interposer 18 defining adesired punch pattern between the punch and the workpiece. Assistance inpunch slug removal may be provided by applying a vacuum 30 on the sideof the punch opposite the impinging gas flow to draw the gas flow acrossthe punch in a direction perpendicular to the reciprocating travel pathof the punch.

Although illustrated and described herein with reference to certainspecific embodiments, the present invention is nevertheless not intendedto be limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the spirit of the invention.

What is claimed:
 1. A method for punching which comprises the steps of:providing a workpiece proximate a surface of a die plate defining anaperture having a cross-sectional area; punching a slug from theworkpiece through the aperture using a punch having a first side, asecond side, and a linear reciprocating travel path with a transitionpoint where the punch changes linear direction; directing a gas flowhaving a velocity through a distribution channel and an orifice definedin a manifold having a substantially planar top surface directlysupporting the die plate; and impinging the gas flow on the slugattached to the punch in a direction perpendicular to the reciprocatingtravel path of the punch, on the first side of the punch, and adjacentthe transition point of the reciprocating travel path of the punch toremove the slug from the punch, wherein the orifice is positioned at thetop surface of the manifold adjacent the transition point of thereciprocating travel path of the punch.
 2. The method of claim 1 furthercomprising the step of applying a vacuum offset relative to the punch,the vacuum enhancing removal of the slug from the punch.
 3. The methodof claim 2 wherein the vacuum is applied on the second side of the punchopposite the impinging gas flow to draw the gas flow across the punch inthe direction perpendicular to the reciprocating travel path of thepunch.
 4. The method of claim 1 further comprising the step of insertingan interposer defining a desired punch pattern between the punch and theworkpiece.
 5. The method of claim 1 further comprising the step ofincreasing the velocity of the gas flow through a tapered distributionchannel.
 6. The method of claim 1 further comprising the step ofreducing the cross-sectional area of the aperture by extending themanifold into the aperture of the die plate.
 7. The method of claim 1further comprising the step of providing the manifold with a step formedunder the punch.
 8. The method of claim 1 further comprising the step ofproviding a die bushing supported by the manifold and disposed in theaperture of the die plate, the die bushing supporting the workpiece andhaving an opening through which the punch and the slug pass.
 9. Themethod of claim 8 further comprising the step of adhering each of thedie plate and the die bushing to the manifold.
 10. A method for punchingwhich comprises the steps of: providing a workpiece proximate a surfaceof a die plate defining an aperture having a cross-sectional area;punching a slug from the workpiece through the aperture using a punchhaving a first side, a second side, and a linear reciprocating travelpath with a transition point where the punch changes linear direction;directing a gas flow having a velocity through a distribution channeland an orifice defined in a manifold having a substantially planar topsurface directly supporting the die plate; providing a die bushingsupported by the manifold and disposed in the aperture of the die plate,the die bushing supporting the workpiece and having an opening throughwhich the punch and the slug pass; impinging the gas flow on the slugattached to the punch in a direction perpendicular to the reciprocatingtravel path of the punch, on the first side of the punch wherein theorifice is positioned at the top surface of the manifold adjacent thetransition point of the reciprocating travel path of the punch, andadjacent the transition point of the reciprocating travel path of thepunch to remove the slug from the punch, wherein the orifice ispositioned at the tip surface of the manifold adjacent the transitionpoint of the reciprocation travel path of the punch; and applying avacuum offset relative to the punch, the vacuum enhancing removal of theslug from the punch.
 11. The method of claim 10 further comprising thestep of inserting an interposer defining a desired punch pattern betweenthe punch and the workpiece.
 12. The method of claim 10 wherein thevacuum is applied on the second side of the punch opposite the impinginggas flow to draw the gas flow across the punch in the directionperpendicular to the reciprocating travel path of the punch.
 13. Themethod of claim 10 further comprising the step of increasing thevelocity of the gas flow through a tapered distribution channel.
 14. Themethod of claim 10 further comprising the step of reducing thecross-sectional area of the aperture by extending the manifold into theaperture of the die plate.
 15. The method of claim 10 further comprisingthe step of providing the manifold with a step formed under the punch.16. The method of claim 10 further comprising the step of adhering eachof the die plate and the die bushing to the manifold.